Value of endomyocardial biopsy in infants, children and adolescents with dilated or hypertrophic cardiomyopathy and myocarditis.

Endomyocardial biopsy was performed in 20 symptomatic pediatric patients with the following clinical diagnoses: dilated cardiomyopathy in 16, hypertrophic cardiomyopathy in 2 and myocarditis in 2. Transfemoral biopsy was performed without complications in patients aged 2 months to 16 years; 6 were less than 1 year old. An average of five right ventricular specimens were obtained for histologic and ultrastructure study from each patient. In 16 patients with the clinical diagnosis of dilated cardiomyopathy, biopsy findings were compatible with the diagnosis in 8, but changed the diagnosis as follows in the other 8: myocarditis, 4; hypertrophic cardiomyopathy, 2 and carnitine deficiency syndromes, 2. In two patients with the clinical diagnosis of hypertrophic cardiomyopathy, biopsy findings confirmed the diagnosis in one and were normal in the other who had an encapsulated cardiac fibroma at operation. In two patients with the clinical diagnosis of myocarditis, biopsy findings confirmed the diagnosis in one and suggested dilated cardiomyopathy in the other. In the entire series, 25% had biopsy evidence of inflammatory disease. Biopsy findings were confirmed at subsequent autopsy in five cases.